Manufacture of cyclopentadienyl-manganese carbonyl compounds



United States atent MANUFACTURE OF CYCLOPENTADIENYL-MAN- GANESE CARBONYL COMPOUNDS Application November 18, 1957 Serial No. 696,954

No Drawing.

6 Claims.

This invention relates to the manufacture of organo metal carbonyl compounds and more particularly to the production of cyclopentadienyl manganese tricarbonyl compounds.

cyclopentadienyl manganese tricarbonyl compounds have been found to be exceptionally effective antiknocks for use in fuel, for spark plug ignition internal combustion engines. Many of these compounds, principally the liquid compounds, additionally have auxiliary properties which make them entirely practical and desirable for commercial use. These auxiliary properties include high solubility in hydrocarbon fuels, such as gasoline, and thermo-stability either alone or in gasolines. Such stability is necessary for use under the widely varying conditions to which gasoline and other fuels are normally subjected. Possibly of even greater importance, these compounds do not tend to form any appreciable deposits on the engine pistons, valves and spark plug surfaces, and

likewise are not abrasive to the engine parts, as are characteristic of iron compounds.

It is accordingly an object of this invention to provide an improved method for manufacture of cyclopentadienyl manganese tricarbonyl compounds. Another object is to provide a process of the above type which gives high conversions to the desired cyclopentadienyl manganese tricarbonyl compounds and which minimizes the formation of undesired by-products. A more specific object is to provide a process which eliminates or materially reduces the production of polymeric by-products which interfere with the recovery of the desired product and which limits the over-all utilization of the starting materials. A specific object is to provide a method of the above type suitable for large scale commercial production of cyclopentadienyl manganese tricarbonyls, particularlyalkylcyclopentadienyl manganese tricarbonyls. Other objects and advantages of this invention will be apparent from the following description and appended claims.

These and other objects of the present invention are accomplished if a cyclopentadienyl manganese salt and carbon monoxide are reacted in the presence of an alkali metal, alkaline earth metal, or an earth metal, i.e. metals of groups IA, IIA or IIIA of the periodic table.

The above process provides considerably greater yields of the desired cyclopentadienyl manganese tricarbonyl compounds than heretofore attained by known methods and at the same time minimizes undesired by-product formation, eg by reducing polymer formation. When, for example, a bis(cyclopentadienyl) manganese compound is reacted With carbon monoxide by the known process, only half of the cyclopentadienyl radicals can theoretically form a part of the product, the other cyclopentadienyl radical becomes polymerized and is a major component of the crude reaction product. Moreover, even using the best techniques now known, only from 30 to 40 percent conversion to product of the initial cyclopentadiene is obtained, whereas when the process is conducted in the presence of a metal in accordance with this invention, greater than 50 percent of the initial cyclopentaice diene is normally utilized in the formation of the desired cyclopentadienyl manganese tricarbonyl product. In addition to the savings obtained in better utilization of the feed materials, the problem of recovery and purification of the desired product is materially simplified due to elimination or reduction of the by-product polymer.

More particularly the process of this invention comprises reacting the cyclopentadienyl manganese salt and carbon monoxide under at least a moderate carbon monoxide pressure, using from about 0.1 mole to about 2 moles of a metal, as defined above, per mole of the cyclopentadienyl manganese salt, preferably mole equivalent quantities, at a temperature of from about 50 to about 300 C., or at least below the temperature at which the product tends to decompose at an unsatisfactory rate. The preferred temperature is between about 100 to 250 C. Although the process can be conducted in the absence of a solvent or diluent, a solvent system is normally preferred.

The cyclopentadienyl manganese tricarbonyl compounds, which can be produced in accordance with the process of this invention, can contain any cyclomatic group having the 5 carbon atom ring such as is found in cyclopentadiene itself. This cyclomatic group can be substituted with one or more monovalent hydrocarbon radicals or can be of a condensed ring type, such as the indenyl or fluorenyl type. The process is particularly suitable for the manufacture of compounds in which the cyclomatic group contains from 5-13 carbon atoms. These compounds, have a molecular weight up to about 315.

Typical examples of cyclopentadienyl manganese tricarbonyl compounds which can be produced by the process of this invention are cyclopentadienyl manganese tricarbonyl, methylcyclopentadienyl manganese tricarbonyl, n-octyl cyclopentadienyl manganese tricarbonyl, diethyl cyclopentadienyl manganese tricarbonyl, phenyl cyclopentadienyl manganese tricarbonyl, benzyl cyclopentadienyl manganese tricarbonyl, indenyl manganese tricarbonyl, fiuorenyl manganese tricarbonyl and the like.

Illustrative examples of other cyclopentadienyl radicals are 2,4-di-methyl-3-tert-butylcyclopentadienyl; isopropenyl cyclopentadienyl, acetyl cyclopentadienyl and the like. The cyclopentadiene radical itself can have from -1 to 5 of one or more of the above substituted radicals. Likewise, the indenyl radical can have from 1 to 7 of any one or more of the above radicals and the fiuorenyl radical can be substituted by l to 9 of the above radicals. Typical examples of indenyl-type radicals are Z-methyl indenyl; 3,4-divinyl indenyl; l-phenyl indenyl; 3-ethyl fluorenyl; 4, 5-dipropyl fluorenyl; 6-vinyl fluorenyl; 4-benzyl-fiuorenyl; Z-m-tolyl fluorenyl and the like. Other examples of suitable cyclomatic radicals include 4,5,6,7-tetrahydroindenyl; 1,2,3,4,5,6,7,8-octahydrofiuorenyl; 3-methyl-4,5, 6,7-tetrahydroindenyl and the like.

The alkali metal can be any of the group IA metals, including sodium, lithium, potassium, rubidium, and

cesium, the preferred metal being sodium from the standpoint of both economics and operation. The alkaline earth metals suitable with this invention are any of the group I-IA metals, including beryllium, magnesium, calcium, strontium and barium. The earth metals are metals of group llI A and include boron, aluminum, gallium, indium and thallium.

Any of a wide variety of cyclopentadienyl manganese salts can be employed in the process of this invention although the hadiles (particularly, the chloride) are preferred. In addition-to the halides, i.e. chloride, bromide, iodide, and fluoride, both inorganic and organic anions can be used. The monovalent anions are preferred. Illustrative examples are cyclopentadienyl manganese chloride, methylcyclopentadienyl manganese bromide, n-

decylcyclopentadienyl manganese iodide, indenyl manganese fluoride, fluorenyl manganese nitride, cyclopentadienyl manganese nitrate, methylcyclopentadienyl manganese acetate; and cyclopentadienyl manganese naphthenate. Other suitable cyclopentadienyl manganese salts are the butyrate, phenate, phosphide, aside, cyanide, thiocynate, isoprepoxide and the like.

The metals which are in a solid state under reaction conditions should preferably be subdivided prior to reaction. Best results are obtained when the metal has a particle size of 5 to 200 microns. The most preferred particle size is from to 50 microns average particle size. A particularly suitable method of preparing the metal is the use of a grinding operation and particularly a ball mill in which the milling is conducted under a suitable solvent, such as those noted above. In fact, optimum results are obtained if the reaction is conducted while ball milling the entire reaction mass.

A convenient method of preparing the cyelopentadienyl manganese salts is by the reaction of a manganese salt, e.g. a halide, with a bis(cyclopentadienyl) manganese compound. In this preparation, essentially stoichiometric quantities are frequently preferred, although an excess of either the manganese halide or the bis(cyclopentadienyl) manganese can be used, generally from 0.5 to 2 moles of manganese halide per mole of the bis(cyclopentadienyl) manganese compound.

The bis(cyclopentadienyl) manganese compounds can be produced by several known methods. In general, these compounds are produced by reaction of an alkali metal, e.g. sodium, with the cyclopentadiene hydrocarbon in a suitable solvent system at a temperature of from 0 to 250 C. and thereafter reaction this product with a manganous salt, e.g. a halide, at temperatures above about 100, preferably above 130 C. The cyclopentadiene hydrocarbon is usually employed in 1 to 20 mole percent excess, based on the moles of alkali metal. Alkali metal compounds, such as sodium hydride and sodamide, can also be employed in the first step. Hydrocarbons, ethers, amines, and other solvents can be employed in the process. Illustrative examples of solvents are hexane, n-decane, mineral oil, cyclopentadiene dimer, benzene, toluene, naphthalene, diphenyl, diphenyl ether, diethyl ether, ethylene glycol dimethyl ether, liquid ammonia, triethanolamine and the like. The reaction of the manganous salt with the cyclopentadienyl alkali metal compound normally requires a solvent and, for this purpose, the ether types give best results. The ethylene glycol dialkyl ethers are preferred. 7

Carbon monoxide can be employed over a wide pressure range, e.g. from 1 to 1000 atmospheres. A more preferred range is from 10 to 100 atmospheres. The carbon monoxide purity is not critical but is important. It s best to use carbon monoxide of 90 to 100 percent purity.

As pointed out above, solvents can be used in the present process and are frequently preferred. The solvent can be the same as used in the preparation of the bis(cyclopentadienyl) manganese compound above. Typical examples of suitable solvents are hydrocarbons, ethers and amines. Suitable hydrocarbon solvents are the parafiin types, such as n-pentane, isopentane, hexanes, heptanes, n-octane and mineral oils; and aromatic types, such as benzene, toluene, xylene, naphthylene and alkylated naphthylenes, e.g. the methylated naphthylenes, and dlphenyl. Illustrative examples of ethers which can be used in this invention are dimethyl ether, methyl ethyl ether, diethyl ether, di-isopropyl ether, diphenyl ether,

and dioxane. The most preferred solvents are the ethylene glycol alkyl ether types, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether and di' ethylene glycoldibutyl ether. Suitable amines useful in carrying out the present invention are dicyclohexylamine, benzylamlne, N-methylaniline, N-ethylaniline, N-ethylnaphthylamine, N,N-dimethylaniline, tri-n-hexylamine,

N-methyl diphenyl amine. Quantities of solvent from 0.1 part to 100 parts per part of manganese compound can be employed. Preferably rather concentrated solutions are used, e.g. from about 0.5 part to about 10 parts per part of manganese compound.

The following are typical examples which illustrate the process of the present invention. All quantities in the following examples are given in parts by weight.

EXAMPLE I Methylcyclopentadienyl manganese chloride prepared from 19 parts of bis(methylcyclopentadienyl) manganese and 11.4 parts of manganese chloride in parts of diethylene glycol dimethyl ether is mixed with 4.4 parts of sodium metal in a pressure reactor equipped with a stirrer and means to feed and vent gases. Upon addition of the sodium to methylcyclopentadienyl chloride, a vigorous exothermic reaction takes place. The reactor is then sealed and the reaction is carried out under carbon monoxide pressure at 165 C. and at 195 C. while agitating the mixture. A pressure drop is observed while operating at maximum pressure of 500 pounds at 165 C. over a period of 2% hours. An additional drop occurs over a period of 2 hours at 195 C. The reaction mixture is discharged from the reactor and any remaining product is washed from the reactor with diethylene glycol dibutyl ether (50 parts). The product is then vacuum distilled to remove the volatile components, including the nwthylcyclopentadienyl manganese tricarbonyl product. The crude product is fractionated to recover essentially pure methylcyclopentadienyl manganese tricarbonyl as the middle fraction. The product is recovered in greater than 50 percent yield based upon the methylcyclopentadienyl manganese chloride reactant.

The product is thereafter further fractionated to obtain a highly pure methylcyclopentadienyl manganese tricarbonyl and this product is then blended with gasoline. The following table shows data with the octane increase of a commercial gasoline having an initial boiling point of 94 F. and a final boiling point of 390 F. The antiknock value of the fuel as determined by the ratings are given in octane numbers for values below and in Army-Navy performance numbers for values above 100. The method of determining performance numbers is explained in the booklet Aviation Fuel and their Effect on Engine Performance, NAVAER 064-501, USAF TD. No. 06-5-54, published in 1951. For numbers below 100, the Research method is employed. The Research method of determining the octane number of a fuel is generally accepted as a method of test which gives a good indication of fuel behavior in full-scale automotive engines under normal driving conditions and the method most used by commercial installations in determining the value of a gasoline or additive. The Research method of testing antiknocks is conducted in a single-cylinder engine especially designed for this purpose and referred to as the CFR engine. This engine has a variable compression ratio and during the test the temperature of the jacket water is maintained at 212 F. and the inlet air temperature is controlled at F. The engine is operated at a speed of 600 rpm. with a spark advance of 13 before top dead center. The test method employed is more fully described in test procedure D-908-55 contained in 1956 edition of ASTM Manual of Engine Test Methods for rating fuels.

EXAMPLE II are considerably lower than those obtained when the added metal is present in the carbonylation reaction.

EXAMPLE III A solution containing 9.2 parts of methylcylclopentadienyl sodium in 85 parts 1,2,-dimethoxyethane is stirred at reflux with 11.3 parts of manganous chloride until the characteristic dark yellow-green solution of methylcyclopentadienyl manganese chloride is obtained. The cooled solution is charged in a nitrogen atmosphere to a pressure reactor along with 3.0 parts of calcium. Carbon monoxide is introduced to a pressure of 3000 p.s.i.g. and the mixture is then heated to 150 C. The pressure is then increased to 3500 p.s.i.g. and maintained at this level until carbon monoxide absorption is complete. The cooled apparatus is then vented and discharged into a steam distillation apparatus. A yellow oil, composed mainly of methylcyclopentadienyl manganese tricarbonyl with smaller amounts of manganese pentacarbonyl (which sometimes appears as crystals), separates from the steam distillate in good yield.

EXAMPLE IV Cyclopentadienyl manganese bromide, prepared in 85 parts of dioxane from 8.3 parts of bis(cyclopentadienyl) manganese and 9.7 parts of manganous bromide, and 2.0 grams active magnesium powder are charged to a pressure reactor. Care is taken to exclude air and moisture from the systems by means of a nitrogen or orgon atmosphere. The mixture is heated to 190 C. under carbon monoxide pressure. The pressure is maintained at 1000 p.s.i.g. until successive readings at 30 minute intervals indicate that carbon monoxide is no longer being absorbed. When reaction is complete, the mixture is cooled and then discharged into 500 parts of water. Extraction of the resulting slurry with 400 parts of benzene yields an organic solution containing cyclopentadienyl manganese tricarbonyl and traces of manganese pentacarbonyl. Evaporation and cooling of the solution results in crystallization of cyclopentadienyl manganese tricarbonyl in high yield.

EXAMPLE V Example I is repeated except that 17 parts of cyclepentadienyl manganese bromide and manganous iodide (31 parts) is reacted with carbon monoxide in the presence of 3 parts of potassium powder. This reaction is carried out in triethylamine solvent parts) at a temperature of 100 C., using 700 p.s.i.g. carbon monoxide pressure.

EXAMPLE VI Example I is repeated except that 14.2 parts of his (indenyl) manganese and manganous acetate (8.7 parts) is reacted in 100 parts of di-n-butyl ether with carbon monoxide at 4000 p.s.i. at C. Two parts of magnesium powder is'employed in the reaction as a reducing agent.

EXAMPLE VII Example I is repeated except that a finely divided aluminum is employed instead of the sodium. The aluminum is first prepared by feeding a rod of pure aluminum into a rotating cutter blade maintained under dry sodium hexane. This subdivided aluminum is then employed in stoichiometric equivalent quantity with methylcylopentadienyl manganese fluoride and 500 p.s.i.g. pressure of carbon monoxide in a ball mill. The ball mill is operated throughout the course of the reaction and materially increases the rate of the reaction.

When the above examples are repeated using calcium, lithium and gallium, similar results are obtained. Also, manganous bromide, manganous acetate, manganous propionate, manganous oxide, manganous nitride and manganous sulfate give similar results.

I claim:

1. The process for producing cyclopentadienyl manganese tricarbonyl compounds comprising reacting a cyclopentadienyl hydrocarbon manganese salt containing a monovalent anion with carbon monoxide and at least 0.1 mole of a metal, selected from metals of groups IA, HA, and IIIA of the periodic table at a temperature of from about 50 to about 300 C.

2. The process of claim 1 wherein the anion of the cyclopentadienyl hydrocarbon manganese salt is a halide.

3. The process of claim 1 wherein the reaction is carried out in an inert solvent.

4. The process of claim 2 wherein the metal is aluminum.

5. The process of claim 2 wherein the cyclopentadienyl group has 5 carbon atoms.

6. The process of claim 2 wherein the cyclopentadienyl group has 6 carbon atoms.

, References Cited in the file of this patent Fischer et a1.: Zeit. Naturforsch. 9b, p. 618 (1954). 

1. THE PROCESS FOR PRODUCING CYCLOPENTADIEBYL MANGANESE TRICARBONYL COMPOUNDS COMPRISING REACTING A CYCLOPENTADIENYL HYDROCARBON MANGANESE SALT CONTAINING A MONOVALENT ANION ITH CARBON MONOXIDE AND AT LEAST 0.1 MOLE OF A METAL, SELECTED FROM METALS OF GROUPS IA, IIA, AND IIA OF THE PERIODIC TABLE AT A TEMPERATURE OF FROM ABOUT -50* TO ABOUT 300*C. 